SAP warns on Q3 earnings:

"The market developments of the past several weeks have been dramatic and worrying to many businesses. These concerns triggered a very sudden and unexpected drop in business activity at the end of the quarter," said Henning Kagermann, Co-CEO of SAP. "Throughout the third quarter we felt quite positive about our ability to meet our expectations. Unfortunately, SAP was not immune from the economic and financial crisis that has enveloped the markets in the second half of September, causing us to report numbers below our expectations."

WSJ: "[T]he current economic slowdown may be different because of the credit crunch; the inability to borrow could force businesses to scale back technology spending because of concerns about not having enough cash for the rest of the business."
Last year, Seeking Alpha said a recession could be especially hard on software-as-a-service vendors:

SaaS on-demand companies' revenue models are typically based on a number of user seats, so in an expanding economy with growth in hiring, SaaS companies are able to grow within their installed base and capture revenues as their clients expand with the economy. In a declining economy, SaaS companies may take a triple hit as they will see their initial transaction sizes trimmed, upsell opportunities reduced or eliminated, and then there is a possibility that users will aim to reduce the number of subscribed seats.